Display apparatus with position input function

Abstract

A liquid crystal display device includes a liquid crystal panel, a housing, a position detection electrode, and a calculation unit. The housing accommodates the liquid crystal panel. The housing is made of conductive made of conductive material and disposed to cover at least a surface of the liquid crystal panel on an opposite side from a display surface of the display panel. The position detection electrode is disposed on the liquid crystal panel such that the position detection electrode and the housing have electrostatic capacitance therebetween and the position detection electrode and a finger have electrostatic capacitance therebetween to detect an input position. The calculation unit is configured to calculate a pressure in a normal direction to the display surface based on a difference in signal regarding the electrostatic capacitance detected when a position change regarding the input position detected by the position detection electrode is within a specified range.

1 . A display device with position input function, the display device comprising:
 a display panel;   a housing accommodating the display panel, made of conductive material, and disposed to cover at least a surface of the display panel on an opposite side from a display surface of the display panel;   a position detection electrode disposed on the display panel such that the position detection electrode and the housing have electrostatic capacitance therebetween and the position detection electrode and a position input body that inputs a position in a plane of the display surface have electrostatic capacitance therebetween to detect an input position of the position input body; and   a calculation unit configured to calculate a pressure in a normal direction to the display surface based on a difference in signal regarding the electrostatic capacitance detected when a position change regarding the input position of the position input body detected by the position detection electrode is within a specified range.   
     
     
         2 . The display device with position input function according to  claim 1 , wherein the calculation unit is configured to calculate the pressure by multiplying the difference by a correction coefficient corresponding to an input position on the display surface. 
     
     
         3 . The display device with position input function according to  claim 1 , further comprising a memory that stores, as a reference value, a signal associated with electrostatic capacitance acquired when a variation associated with an input position detected by the position detection electrode exceeds a threshold, wherein
 the calculation unit calculates the pressure based on a difference between a signal associated with electrostatic capacitance acquired when the variation does not exceed the threshold, and the reference value stored in the memory.   
     
     
         4 . The display device with position input function according to  claim 3 , wherein the memory stores, as the reference value, a peak value in the signal associated with the electrostatic capacitance acquired when the variation exceeds the threshold. 
     
     
         5 . The display device with position input function according to  claim 1 , wherein:
 the housing includes a bottom portion that covers the surface of the display panel opposite to the display surface; and   the bottom has a shape curved such that a distance between the bottom portion and the display panel gradually decreases from a central region of the display surface toward an end region of the display surface.   
     
     
         6 . The display device with position input function according to  claim 1 , wherein:
 a driver configured to drive the position detection electrode is mounted on the display panel; and   the calculation unit is included in the driver.   
     
     
         7 . The display device with position input function according to  claim 1 , the display device further comprising:
 a connection part one end of which is connected to the display panel; and   a control circuit board connected to the other end of the connection part, wherein   the calculation unit is included in the control circuit board.   
     
     
         8 . The display device with position input function according to  claim 1 , wherein the calculation unit does not calculate the pressure when the difference does not exceed a threshold, but calculates the pressure when the difference exceeds the threshold. 
     
     
         9 . The display device with position input function according to  claim 1 , wherein the position detection electrode is formed within the display panel. 
     
     
         10 . The display device with position input function according to  claim 9 , wherein:
 the display panel includes at least a pixel electrode to which voltage is applied with gradation corresponding to an image displayed on the display surface, and a common electrode to which common potential is applied; and   the common electrode includes a plurality of divisional common electrodes disposed in a matrix in the plane of the display surface, and constituting the position detection electrode.   
     
     
         11 . The display device with position input function according to  claim 10 , wherein the display panel includes at least a plurality of wires each of which is individually connected to the corresponding one of the plurality of divisional common electrodes. 
     
     
         12 . The display device with position input function according to  claim 10 , wherein:
 the display panel includes at least a pair of substrates overlapped with the display panel on the housing side and on the opposite side, respectively; and   the position detection electrode is provided on the substrate disposed on the housing side as one of the pair of substrates.